public class SingleLinkedList implements List{
    static class ListNode{
        public int val;
        public ListNode next;
        public ListNode(int val){
            this.val=val;
        }
    }
    public ListNode head;
    public boolean isEmpty(){
        return head==null;
    }
    //头插法
    public void addFirst(int data){
        ListNode node= new ListNode(data);
        if(isEmpty()){
            head=node;
            return;
        }
        node.next=head;
        head=node;
    }
    //尾插法
    public void addLast(int data){
        ListNode node= new ListNode(data);
        if(isEmpty()){
            head=node;
            return;
        }
        ListNode cur=head;
        while (cur.next!=null){
            cur=cur.next;
        }
        cur.next=node;
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index, int data){
        if(index<0||index>this.size()){
            System.out.println("index越界");
            return;
        }
        if(index==0){
            addFirst(data);
            return;
        }
        if(index==this.size()){
            addLast(data);
            return;
        }
        ListNode node=new ListNode(data);
        ListNode cur=head;
        while (index-1>0){
            cur=cur.next;
            index--;
        }
        node.next=cur.next;
        cur.next=node;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur=head;
        while (cur!=null){
            if(cur.val==key){
                return true;
            }
            cur=cur.next;
        }
        return false;
    }

    //删除第一次出现关键字为key的节点
    public void remove(int key) {
        ListNode cur=head;
        if(head.val==key){
            head=head.next;
            return;
        }
        while (cur!=null){
            ListNode curN=cur.next;
            if(curN.val==key){
                cur.next=curN.next;
                return;
            }
            cur=cur.next;
        }
    }

    //删除所有值为key的节点
    public void removeAllKey(int key) {
        if(head.val==key){
            head=head.next;
        }
        ListNode cur=head;
        while (cur!=null&&cur.next!=null){
            ListNode curN=cur.next;
            if(curN.val==key){
                cur.next=curN.next;
            }
            cur=cur.next;
        }
    }

    //得到单链表的长度
    public int size() {
        ListNode cur=head;
        int count=0;
        while (cur!=null){
            cur=cur.next;
            count++;
        }
        return count;
    }

    public void display() {
        ListNode cur=head;
        while (cur!=null){
            System.out.print(cur.val+" ");
            cur=cur.next;
        }
        System.out.println();
    }

    public void clear() {

    }
}
